The use of pipette devices for the transfer and dispensing of precise quantities of fluids in analysis is well known. Likewise, disposable plastic tips used with pipetting devices have been commercially available for decades. These tips are used with pipetting devices that may use 1, 8, 12, or 96 tips simultaneously, and are usually packed vertically in a pipette tip rack.
The function of a pipette tip rack is to organize disposable pipette tips in a manner for convenient placement on a pipette. A pipette tip rack is usually a plastic container or box that has a number of holes, 96 for example, into which pipette tips are placed. A rack with 96 holes has the holes arranged typically in an eight by twelve array that is spaced approximately 9 mm apart on their centerlines. Generally, such racks comprise a rigid base with substantially vertical sides joined with a flat supporting plate that holds an array of pipette tips in holes that extend through the plate. Pipette tips are organized and held vertically by the array of holes for ease of access. A human worker or a mechanical pipetting device simply places a pipette over the rack and lowers the distal end of the pipette into a proximal or upper end of a vertically oriented pipette tip and presses down to affix the tip, which is held to the pipette by friction.
After all the pipette tips are used the customary practice has been either to reload the rack by hand with new pipette tips purchased in bulk or dispose of the empty rack. Presently, these two customary practices each present significant disadvantage. The disadvantage or inconvenience of reloading the tips into the rack by hand is that the operation is a very time consuming process for lab workers who are generally over qualified for such repetitious work, as well, as the pipette the tips may become contaminated by manual handling. The disadvantage of disposing of the rack is that it ordinarily consists of three molded parts that still retain some value, namely the rack, itself, a cover to enclose the tips, and a base-plate to enclose and seal the bottom of the rack. Since tips are often used in large quantities, disposing of many bulky racks is wasteful and environmentally harmful. As a result, manufacturers are paying more attention to the issues that effect coat and storage space requirements, and the environment. This attention, in turn, has generated a desire to eliminate or reduce the amount of packing required to ship and store products. These concerns have driven the need to develop a new design for a pipette-tip rack.
The new design creates a reusable pipette-tip rack, conceptually, made by the joining of two standard pipette-tip racks, base-to-base, to form a rigid box or container with a central cavity. More significantly, the new design doubles the density of the number of pipette tips that can be contained in a single box or package. For example, a pipette-tip rack having a 96 hole-matrix will have pipette tips arranged in the typical eight by twelve array, however, according to the present invention, the tips are loaded into the container from both the top and bottom of the box. By off-setting the centerline spacing of the rows of holes on both top and bottom horizontal surfaces from one side of the box to the other side by approximately 4.5 mm, the new rack design is able to accommodate twice the number of pipette tips over and against other pipette tip racks that are currently available in the market. The new design interlocks or nests rows of pipette tips from one side of the box in the interstitial space, or free space, between adjacent rows of tips on the other side of the box. Thus, the proposed pipette-tip rack conserves both the amount of space for storage and material needed in manufacture. The new packaging design reduces the amount of packaging required for shipping and storing products with the use of the least amount of space, while increasing the number of pipette tips available for use within a single package.